Use explicit bind for u_Lights UBO when possible

Get rid of the requirement to not use binding point 0 for UBOs explicitly.

Author: VReaperV

src/engine/renderer/Material.h

@@ -308,9 +308,10 @@ struct SurfaceCommandBatch {
 
 namespace BufferBind {
 	enum : uint32_t {
-		MATERIALS = 1, // LightTile UBO uses binding point 0, so avoid it here
+		MATERIALS = 1,
 		TEX_DATA = 6,
 		LIGHTMAP_DATA = 2,
+		LIGHTS = 0,
 		SURFACE_DESCRIPTORS = 0,
 		SURFACE_COMMANDS = 1,
 		CULLED_COMMANDS = 2,

src/engine/renderer/gl_shader.cpp

@@ -286,7 +286,7 @@ void GLShaderManager::UpdateShaderProgramUniformLocations( GLShader* shader, Sha
 		uniform->UpdateShaderProgramUniformLocation( shaderProgram );
 	}
 
-	if( glConfig2.uniformBufferObjectAvailable ) {
+	if( glConfig2.uniformBufferObjectAvailable && !glConfig2.shadingLanguage420PackAvailable ) {
 		// create buffer for storing uniform block indexes
 		shaderProgram->uniformBlockIndexes = ( GLuint* ) Z_Malloc( sizeof( GLuint ) * numUniformBlocks );
 
@@ -416,6 +416,7 @@ struct addedExtension_t {
 static const std::vector<addedExtension_t> fragmentVertexAddedExtensions = {
 	{ glConfig2.gpuShader4Available, 130, "EXT_gpu_shader4" },
 	{ glConfig2.gpuShader5Available, 400, "ARB_gpu_shader5" },
+	{ glConfig2.shadingLanguage420PackAvailable, 420, "ARB_shading_language_420pack" },
 	{ glConfig2.textureFloatAvailable, 130, "ARB_texture_float" },
 	{ glConfig2.textureGatherAvailable, 400, "ARB_texture_gather" },
 	{ glConfig2.textureIntegerAvailable, 0, "EXT_texture_integer" },
@@ -620,6 +621,10 @@ static std::string GenFragmentHeader() {
 		str += "#define baseInstance in_baseInstance\n\n";
 	}
 
+	if ( glConfig2.shadingLanguage420PackAvailable ) {
+		AddDefine( str, "BIND_LIGHTS", BufferBind::LIGHTS );
+	}
+
 	if ( glConfig2.usingMaterialSystem ) {
 		AddDefine( str, "BIND_MATERIALS", BufferBind::MATERIALS );
 		AddDefine( str, "BIND_TEX_DATA", BufferBind::TEX_DATA );

src/engine/renderer/gl_shader.h

@@ -1231,12 +1231,13 @@ class GLUniformBlock
 protected:
 	GLShader   *_shader;
 	std::string _name;
-	size_t      _locationIndex;
+	size_t      _locationIndex; // Only valid if GL_ARB_shading_language_420pack is not available
+	const GLuint _bindingPoint; // Only valid if GL_ARB_shading_language_420pack is available
 
-	GLUniformBlock( GLShader *shader, const char *name ) :
+	GLUniformBlock( GLShader *shader, const char *name, const GLuint bindingPoint ) :
 		_shader( shader ),
 		_name( name ),
-		_locationIndex( 0 )
+		_bindingPoint( bindingPoint )
 	{
 		_shader->RegisterUniformBlock( this );
 	}
@@ -1258,10 +1259,15 @@ class GLUniformBlock
 	}
 
 	void SetBuffer( GLuint buffer ) {
+		if ( glConfig2.shadingLanguage420PackAvailable ) {
+			glBindBufferBase( GL_UNIFORM_BUFFER, _bindingPoint, buffer );
+			return;
+		}
+
 		ShaderProgramDescriptor *p = _shader->GetProgram();
-		GLuint blockIndex = p->uniformBlockIndexes[ _locationIndex ];
+		GLuint blockIndex = p->uniformBlockIndexes[_locationIndex];
 
-		ASSERT_EQ(p, glState.currentProgram);
+		ASSERT_EQ( p, glState.currentProgram );
 
 		if( blockIndex != GL_INVALID_INDEX ) {
 			glBindBufferBase( GL_UNIFORM_BUFFER, blockIndex, buffer );
@@ -3599,7 +3605,7 @@ class u_Lights :
 {
  public:
 	u_Lights( GLShader *shader ) :
-		GLUniformBlock( shader, "u_Lights" )
+		GLUniformBlock( shader, "u_Lights", BufferBind::LIGHTS )
 	{
 	}
 

src/engine/renderer/glsl_source/computeLight_fp.glsl

@@ -153,7 +153,11 @@ struct Light {
 	float angle;
 };
 
+#if defined( HAVE_ARB_shading_language_420pack )
+layout(std140, binding = BIND_LIGHTS) uniform u_Lights {
+#else
 layout(std140) uniform u_Lights {
+#endif
 	Light lights[MAX_REF_LIGHTS];
 };
 

src/engine/renderer/glsl_source/lighttile_fp.glsl

@@ -45,7 +45,11 @@ struct Light {
 	float angle;
 };
 
+#if defined( HAVE_ARB_shading_language_420pack )
+layout(std140, binding = BIND_LIGHTS) uniform u_Lights {
+#else
 layout(std140) uniform u_Lights {
+#endif
 	Light lights[MAX_REF_LIGHTS];
 };